The present invention relates generally to post-mix beverage dispensing valves and in particular to such valves having active ratio control apparatus.
Post-mix beverage dispensing valves are well known in the art and are typically used to mix together two beverage constituents at a desired ratio to produce and dispense a finished drink. Such constituents generally consist of a concentrated syrup flavoring and a diluent comprising carbonated or uncarbontaed water. Various control strategies have been employed to maintain the desired syrup to water ratio. xe2x80x9cPistonxe2x80x9d type flow regulators are a well known purely mechanical system that employ spring tensioning of pistons that constantly adjust the size of orifice flow openings to maintain the desired ratio between the fluids. However, a failing with such systems is that they require both fluids to be held within relatively narrow flow rate windows in order to work effectively. As is well understood, differences in ambient temperature, syrup viscosity, water pressure and the like can all conspire to affect one or both of the flow rates to a degree that the drink is ratioed improperly becoming either too dilute or too concentrated. As a result thereof, a drink that is too sweet can waste syrup costing the retailer money, and whether too sweet or not sufficiently so, presents the drink in less than favorable conditions, also reflecting negatively on the retailer as well as the drink brand owner. Volumetric piston dispense systems, as differentiated from the above piston based flow regulators, attempt to measure the volumes of each liquid using the known volume of a piston and the stroke thereof. Thus, two pistons, one for the syrup and one for the water are driven simultaneously by the same shaft or drive mechanism and are sized to reflect their desired volume ratio difference. Thus, operation of both pistons serves to move the desired volume ratio of each of the fluids from separate sources thereof to the dispense point or nozzle of the valve. However, these systems have met with difficulty in that there inherently exists a mechanical complexity relative to providing for inlet and outlet lines to each piston and providing for the correct timing of the opening and closing of such lines. Such complexity increases cost, imposes manufacturing difficulties and reduces operating reliability. Also, there exist size constraints that require the pistons to be relatively small resulting in high operating speeds that lead to corresponding seal and other mechanical wear issues, as well as undesired pumping phenomena where less than a full volume is moved with each pump stroke. Naturally, such wear and pumping inaccuracy problems can negatively impact the ratio accuracy.
Electronic post-mix valves are also known that utilize sensors for determining the flow rate of either the water, the syrup or both, and then, through the use of a micro-controller, adjust xe2x80x9con the flyxe2x80x9d the flow rates of either or both of the water and syrup. In addition, hybrid systems are known that utilize both a volumetric piston approach for the syrup and a flow sensing of the water flow. However, such post-mix valves continue to be plagued with cost and reliability problems. The sensors, for example, can be both costly and unreliable. Thus, maintenance of such post-mix valves by trained service technicians remains a large part of the life cost thereof. In general, it appears that the ratioing technology employed in such electronic valves, while useful in large scale fluid ratioing applications, does not translate well into the relatively small size requirements required of such valves.
Accordingly, there is a great need for a post-mix valve that can accurately maintain the proper drink ratio consistently over time regardless of changes in temperature, flow rate and so forth and that is low in cost both as to the purchase price and the maintenance thereof.
The present invention comprises a post-mix beverage dispensing valve that provides for automatic and accurate fluid beverage constituent ratioing, and that is reliable and relatively inexpensive to manufacture and operate. A valve body is designed to be easily assembled and disassembled by hand without the need for hand tools, and includes a water flow body and a syrup flow body releasably securable to a common nozzle body portion. The water and syrup flow bodies each include a horizontally extending flow channel fluidly intersecting with a vertically extending flow channel. The horizontally extending channels of the water and syrup flow bodies each include open ends for connection to sources of water and syrup respectively, and include fluid flow sensors. When secured together, the water, syrup and nozzle bodies are securable as an intact unit to an L-shaped support plate having a horizontally extending base portion and a vertically extending connection facilitating end. A quick disconnect block provides for releasable fluid tight sealing with the open ends of the horizontal water and syrup channels and, in turn, releasable fluid tight sealing with fittings extending from a beverage dispense machine. The bottom end of the support plate includes a hole centered below a bottom end of the nozzle body through which a nozzle is secured to the nozzle body. Water and syrup channels in the nozzle body deliver the water and syrup thereto for mixture within the nozzle for dispensing there from into a suitable receptacle positioned there below. The syrup channel in the nozzle body includes an adjustment setting mechanism that serves as a gross setting for the syrup flow rate within a certain desired range.
The water body horizontal channel flow sensor is of the turbine type and disposed in the channel and includes hall-effect electronics for determining the rotational velocity of the turbine. That velocity information is provided to a micro-controller for determining the flow rate of the water. The syrup body horizontal channel sensor comprises a pair of strain gauge type pressure sensors mounted to and in an exterior wall portion of that channel and extending there through so that the operative parts thereof are presented to the syrup stream. The sensors are also connected to the micro-controller and are positioned on either side of a restricted orifice washer positioned in the flow stream. The syrup flow sensors serve to sense a differential pressure from which the flow rate of the syrup can be interpolated by the micro-controller.
The vertical flow channel of the water body has a stepper motor secured to a top end thereof and a xe2x80x9cVxe2x80x9d-groove type flow regulator and valve seat at an opposite bottom end thereof. An actuating rod extends centrally of the vertical flow channel and is operated by the stepper motor to move linearly therein. The rod includes a tapered end for cooperative insertion through the center of a coordinately tapered central hole of the V-groove regulator. A tip end of the tapered rod end cooperates sealingly with a seat to regulate flow of the water past the seat and into the nozzle body. The stepper motor is connected to a suitable power source and its operation is controlled by the micro-controller.
A solenoid having a vertically extending and operating armature is secured to a top end of the vertical flow channel of the syrup body. The armature is operable to move in a downward direction through the vertical syrup flow channel and has a distal end that cooperates with a seat formed in the nozzle body positioned centrally of that vertical flow channel at a bottom end thereof. The solenoid is also connected to a suitable power supply and controlled by the micro-controller.
An outer housing is secured to the support plate and serves to cover and protect the valve body sections, actuating devices and an electronics board containing the electronic micro-controller based control. The valve can be actuated by various means including, a lever actuated micro-switch or one or more push switches on the front face of the valve.
In operation, actuation of a valve switch causes the syrup solenoid to open and the stepper motor to retract the linear rod to a predetermined position away from its seat. The syrup and water then flow through the nozzle body to the nozzle and are subsequently mixed together for dispensing into a cup of other receptacle. As the water is flowing, it rotates the turbine flow sensor and the rotational speed thereof is translated into a flow rate by the micro-controller. At the same time, the differential pressure sensors are sensing the pressures on each side of the restricted orifice and the micro-controller is, based on that information, calculating a flow rate for the syrup. It will be appreciated by those of skill that the position of the linear rod tapered end vis a"" vis the v-groove regulator, changes the size of the opening leading to the nozzle body through which the water must flow. Thus, the flow rate of the water can be adjusted in that manner in proportion to the size of that opening whereby the stepper motor can be actuated to position the linear rod tapered end at any point between full open and full closed. Therefore, in the valve of the present invention, the micro-controller first determines the flow rate of the syrup and then adjusts the flow rate of the water accordingly in order to maintain a pre-programmed ratio between the two liquids at a preprogrammed or desired flow rate. A gross adjustment of the syrup flow rate is provided by the adjustment means in the nozzle body and serves to determine a range as, for example, between a high flow and low flow application, such as, between a 1xc2xd or 4 ounces per second dispense rate.
A major advantage of the preset invention is the combination of the adjustable linear actuation of the rod that interacts with v-groove regulator to regulate the flow rate of the water. This approach is quite accurate, is reliable and low in cost. Determining the flow rate of the water through the use of a turbine flow meter has also proven reliable and low in cost. A further major advantage of the present invention is the use of a microelectronic strain gage type differential pressure sensor approach for determining the syrup flow rate. Syrup has proven to be a difficult substance to work with owing in large part to its viscosity, the temperature sensitivity of that viscosity and that it can be corrosive and harbor the growth of microorganisms. The microelectronic sensors have been found herein to be suitable for use with beverage syrups in that they are able to accurately sense variations in the flow rate thereof without much effect as to viscosity changes, and are not degraded chemically over time. In addition, the particular mounting of the sensors requires a very small area of contact with the syrup resulting in a structure that does not cause any type of syrup build up or cleanliness concerns. The syrup flow sensing approach of the present invention provides the further advantage of also providing for a valve that is relatively compact, light in weight and low in cost.
The ability of the valve of the present invention to be disassembled by hand, including the internal components of the water, syrup and nozzle bodies provides for ease of manufacture and repair thereby also reducing the resultant purchase and life costs thereof.